Method of making electromagnetic contactors



Oct. 18, 1955 A. P. CHARBONNEAU ETAL 2,720,693

METHOD OF MAKING ELECTROMAGNETIC CONTACTORS Original Filed D60. 15, 194-4 United States Patent METHOD OF MAKING ELECTROMAGNETIC CONTACTORS Allan P. Charbonneau and Frank J. Russell, Wauwatosa, Wis., assignors to Cutler-Hammer, 1112., Milwaukee, Wis., a corporation of Delaware Original application December 15, 1944, Serial No. 568,316, now Patent No. 2,575,095, dated November 13, 1951. Divided and'thisapplication March 9, 1951, Serial No. 214,771

2 Claims. '(Cl. 29-155.56)

This invention relates to improvements in electromagnetic contactors, and more particularly to a method of and means for producing electromagnetic contactors having high sealed pull.

The present application is a division of our application Serial No. 568,316, filed December 15, 1944, now Patent No. 2,575,095, issued November 13,1951.

Providing a contactor plunger with an integral flange to seat when the plunger-face seats against its associated stationary core has heretofore been used to increase the sealed pull on such plungers. In practice the obtaining of simultaneous seating of the flange and the plunger face has been difficult and has necessitated laborious-fitting and grinding operations with respect to the plunger flange and the part against which it seats. The object of the present invention is to provide a simple and expeditious method and means for obtaining such simultaneous seating of the plunger face and flange during the assembly of certain parts of an electromagnetic contactor whereby high sealed pull on such plunger is insured.

Another object is-to construct and assemble a plunger and associated parts so as to provide for sealing of the plunger flange as an incident to initial engagernentof the plunger face with its associated stationary core member.

-Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings 'illustratean embodiment of the invention which will now be described; it being understood that the embodiment illustrated is susceptible of modification in respect of certain structural details thereof "and/or in respect of the manner of assembling certain of the parts.

In the drawings,

Figure '1 is an enlarged central sectional view of a contactor constructed in accordance with our invention;

Fig. 2 is an actual size plan view of the device, viewed from the left-hand side of'gFig. 1,;

Fig. 3 is a 'view, partly in elevation and partly in section, of a sub-assembly'of certain parts illustrated in Fig. l, and V Fig. 4 is a transverse section on the-line 44 of Fig. 3, showing the means affording a drive fit .of the bushing with respect to the flanged plunger of Fig. 1.

In the drawings the numeral designates a base molded from any suitable insulating material. We refer to-employ either the molding material sold under the trade-name of Melmac or the molding material sold under the trade-name of 'Bakelitef -When base '10 is composed of Bakelite we prefer to mold or embed in-one face thereof a pair of 'likesheet steel pole ,pieces 11, '11 which define the major portion of the length of the bottom wall of a transverse groove; the plane of which bottom wall'is indicated by numeral 12. The adjacent ends of pole pieces 11 are spaced from each other a distance only slightly greater than the diameter of a .circular opening 13 formed in'base 1'0, and the outer .ends of said pole pieces are spaced only slightly from the opposite ends 14 and 15 of said base. Said pole pieces 11 are preferably provided at opposite sides thereof with upstanding fiange portions (not shown) which extend a distance approximately equal to the diameter'of the contact tips and along the sides thereof. The outer edgesof said flange portions are preferably coplanar with the outer surface of said base. Said pole pieces therefore act in a known manner to assist in extinguishing any arcs which may be formed.

Each of the two stationary contacts comprises aflat and relatively thick punched plate 16 of metal of .good electrical conductivity (preferably copper) having rounded ends 17 and 18, respectively. Each plate .16 is provided, in a concentric relationship to the rounded end 17 thereof, with a relatively large tapped opening 19 which is adapted to threadedly receive the shank 20 of a terminal bolt, the polygonal head of which is designated by numeral '21. After complete threading of each shank 20 into an opening 19 the material of plate 16 is ring-staked aronnd'said opening 19, as indicated at 22, to lock said parts against relative movement, and to provide low resistance electrical contact.

Pole pieces 11 are provided respectively with openings 23 and base 10 is provided with openings 24 respectively alined therewith to provide for slidable insertion of shanks 20 therethrough. A screw has its threaded shank 25 freely penetrating alined openings in base 10 and in the respective pole piece '11 and taking into a tapped opening 26 in each plate 16 to rigidly secure the latter and its associated terminal bolt to said base. The head 27 of each screwis preferably accommodated within a countersink or recess in base 10, and a lockwasher 28 of suitable form is also preferably positioned between the screw-head-and the bottom wall of the recess. If desired the remainder of each recess may be filled with a suitable wax or cement (not shown) to additionally restrain the screws and insulate the heads 27 thereof.

Prior to assembly of each plate 16 with respect tobase 10 as aforedescribed said plates have attached thereto in any suitable manner the silver base contact tipsdesignated bynurneral 29. In practice it is-preferred-that plates 16 be prepared in the manner disclosed in Patent 'No. 2,361,089, granted October 24, 1944, to I. W. Cox, and that a suitable metallic composition in powder form be united therewith by molding in the manner disclosed in said patent.

The shank 29 of each terminal bolt has threadedthereonto a nut 30 which assists in rigidly attaching the same and its associated plate 16 to base 10; a lockwasiier 31 of well known form .preferablybeing interposed between said nut 30 and base 10. A second nut 30 is also thereafter threaded onto each shank 20 to act as a clamp or binding element for the bared end of a circuit wire (not shown) which is preferably located between a metal washer 32 and the inner nut 30. A split lockwasher 53 is preferably interposed between washer 32 and the outer nut 30 to prevent accidental loosening of the latter.

The operating coil of the contactor is designated by numeral 34, said coil being wound in a-known manner and impregnated with a suitable material to insure against failure thereof when in use. All surfaces of coil 34 are provided with a suitable insulatingcoven'ng, as indicated by numerals 35, 36, 37 and 38. Said coil as thus covered is positioned within a seamless cup-shaped shell 39, preferably formed of steel; said shell having at its open end an outwardly offset or slightly enlarged portion 40, whereby a shoulder 41 is provided.

A relatively thin tube .2 of non-magnetic material such as brass is adapted to fit snugly within the central passage or opening in coil 34; said tube having positioned at-one end thereof, and rigidly and permanently attached thereto in any suitable manner, a core member 43 .formed of magnetic material such as steel. Member 43 is provided at one end with a concentric countersink 44 and tapped recess 45; the former being adapted to freely slide over the cylindrical enlarged portion .46 of a specially formed attaching bolt, whose threaded shank 47 takes into recess 45.

form; a lockwasher54 being interposed between the same and bracket arm 50. Thus upon tightening of said bolt the shank '47 draws core member 43 into direct engagement with the inner surface-ofthe end wall 55 of the shell; the metal tube 42 being simultaneously moved therewith to the assembled position thereof illustrated.

Thereafter an annular punched plate 56 of insulating material, such asflBakelite is inserted within the enlarged portion 39 of the shell, in a relation to closely surround and assist in positioning the projecting end of tube 42. A

steel cup washer 57 is then inserted into said enlarged portion 40 of the shell; said cup washer having an outer annular flange 58 adapted to slidably fit within said enlarged portion, and an inner, relatively shorter, annular flange 59 adapted to surround at least a portion of the projecting end of tube 42.

The plunger of the contactor is composed of magnetic material, the same having a substantially cylindrical main portion 60 and an integral annular flange 61 at the outer end thereof. As shown the end 62 of the aforementioned core 43 is preferably of substantially cone-shape, and the adjacent end of plunger 60 is correspondingly of hollow cone-shape, as shown at 63 to fit snugly thereagainst. The arrangement is such that flange 61 overlies the upper edge of the inner flange 59 on the cup washer, so that'when plunger 60 is pressed inwardly until the surface 63 seats firmly against the cone-shaped surface 62, the flange 61 will have simultaneously engagedflange 59 to force the cup washer 57 the desired distance into the metal shell. 7

In this manner simultaneous sealing of surface 63 with surface 62 and of flange 61 against flange 59 may be insured. After cup washer 57 is'thus properly positioned,

such positioning may be made'rigid and permanent in any suitable manner, such as by welding or'soldering said cup washer and shell to each other.

The bridging contactor comprises a fiat punched plate 66, preferably of copper; said plate having circular tips 29, 29, like those aforedescribed, rigidly attached to opposite ends thereof. Said contactor tips 29 are properly spaced (see Fig. 1) for alinement thereof with tips 29 of V the stationary contacts. Plate 66 preferably has its ends 67 and 68 rounded to conform substantiallyiwith the contours of the tips-29 mounted thereon. Said plate 66 is also provided with a central circular opening 69, within which an insulating bushing 70 is positioned; said bushing '70 being preferably molded in situ. Bushing 70 is preferably composed of Meltnac, which is characterized by its effective resistance to damage by heating or arcing. Bushing 70 has formed integrally therewith the annular flanges 71 and 72, which overlie the respective opposite faces of plate'66 around said opening 69. A recess 73 is formed in bushing 70 to accommodate the substantially correspondingly shaped cup washer 74, which is preferably formed of brass.

A coiled compression spring 75 has one end seated within cup washer 74; a metal pin 76, proferably of steel, penetrating alined central openings'in bushing 70 and cup washer 74, and having anannular groove 77 formed therein adjacent'one end thereof. A horseshoe-shaped washer 78 is pressed into groove '77, and a metal cup washer 79 is positioned upon pin 76 to surround Washer 78 and prevent accidental lateral displacement thereof; the other end of spring 75 abutting against the exterior surface of cup washer 79. I V

The outer surface 80 of bushing 70 is preferably in the form of asegment of a sphere, for cooperation with the correspondingly shaped concave bearing surface 81'upon a molded hollow insulating member 82, also preferably composed 'of Melmac. Member 82 has a relatively short inner flange 83 and a relatively longer outer flange 84, between which one end of a coiled compression spring 85 (Fig. 1) is adapted to'seat. Prior to assembly of spring 85, however, the threaded end portion 86 of'pin 76 is screwed into the internally threaded portion 87 of a bushing 88, preferably machined from a steel rod. The edge of the aforementioned flange 83 is adapted to abut against the adjacent end of bushing 88, whereby upon a predetermined degree of turning of pin 76 relatively to bushing 88, spring 75 will be compressed to a degree to insure the desired pressure of the bridging contactor against the stationary contacts when all of the parts are finally assembled. In other words, the adjustment of pin 76 with respect to bushing 88 is merely su chas to provide the desired degree of compression of spring 75,-as measured in pounds. When the desired adjustment hasbeen efiected, a quantity of molten solder 89 or the like is dropped into the end of bushing 88 to overlie and surround the reduced end portion 90 of pin 76 to restrain said parts against further movement relatively to each other. Bushing 88 is provided with an end portion '91 of reduced external diameter, toward which the intermediate portion 92 is tapered as shown. The main body portion of bushing 88 has .four equally spaced longitudinal grooves formed therein by rolling or otherwise in such manner that four pairs of longitudinal fins or projections- 93 are provided (Figs. 3Vand 4). Fins 93 are of such lateral dimensions as to provide for a force fit of bushing 88 into a recess 94 in the outer end of plunger 60; bushing 88 being pressed inwardly to a degree to afford the proper wear allowance of bridging contactor 66. q 7

A relatively thin walled molded insulating cover member 95 is provided to house or enclose contactor 66; said member 95 having a pair of openings formed therein (one on each side of the hollow dome or extension 96, Fig. 1). Base 10 has a pair of upstanding lugs formed integrally therewith on opposite sides of the groove 12; one of said lugs being shown at 97 in Fig 1. Said lugs serve to guide the reciprocating movements of contactor 66,-and each .of said lugs has molded therein and projecting outwardly therefrom a'threaded stud (not shown) respectively penetrating said openings in cover 95; a pair of nuts (not shown) being threaded onto said studs to clamp cover 95 in proper position upon base 10. 7 r

The'aforementioned bracket arm 51 is'provided with perforations (Fig. 1) to be alined with the tapped recesses in metal inserts 98, 98 in base 10; suitable screws 99'and lock-washers 100 being provided for clamping said bracket arm and its associated parts to base 10. w 7

The connecting portion 101 of the bracket is provided with openings 102 and 103 to accommodate the shanks of suitable mounting bolts or screws (not shown) forattachment of the complete device to a panel or other suitable support. The aforementioned arm 50 of the supporting'bracket is provided with a relatively small opening 104 which is adapted to accommodate a raised portion or boss 105 formed upon the end wall 55 of shell 39, whereby rela tive rotation of the Shell and bracket is prevented. 'Although said bracket, is formed of relatively thin sheet metal, the same is provided'with suitable embossed ribs and fillets, as shown, to strengthen the same ,and resist distortion thereof when in use.

As shown 'in Fig. 2, base 10 is provided with an integral extension 106 having a downwardly offset ledge 107, which is adapted to accommodate, in a substantially flush relationship, the lateral extensions of the insulating mem- W at bers or plates 37 and 56 (Fig. 1), such extension of plate 37 being designated by numeral 108 in Fig. 2. Interposed between said extensions are a pair of relatively thin copper ribbons, shown in dotted lines at 109 and 110; said ribbons being attached to opposite ends of the wire of coil 34 and having enlarged ends in the form of eyelets which are upset over the outer surface of plate 37, as indicated at 111 and 112 in Fig. 2. Screws 113 and 114 have their shanks extending upwardly through alined openings in base extension 106, plates 56 and 37 (and eyelets 111, 112), and one or more nuts 115, 116 are associated with said screws to clamp the parts in position and to provide for attachment of suitable terminal wires. If desired a bus member 117 may be interposed between screw 114 and one of the screws 99 to provide for grounding of the coil circuit.

We claim:

1. In the method of manufacture of an electromagnetic contactor having a cup-shaped metal shell, an operating coil within said shell and seated against the end of the latter, a core member within said coil abutting against the end of said shell, a cup-shaped metal washer overlying said coil within said shell and provided with an inner annular flange concentric with its outer wall and a plunger movable within said coil provided with a flanged end for engaging the flange of said washer simultaneously with the seating of said plunger against said core member, said method comprising securing the core member to the end of the shell within the coil, inserting the washer into said shell, introducing the plunger into said coil, pressing said plunger inwardly of said coil to first engage its flange with the flange of said washer and then move the latter inwardly of said shell until said plunger seats against said core member, and securing the outer wall of said washer to the inner surface of said shell in the position thus attained, whereby simultaneous seating of the plunger against said core member and the flange of said washer will thereafter be insured.

2. In the method of manufacture of an electromagnetic contactor having a cup-shaped metal shell, an operating coil within said shell and seated against the end of the latter, a core member within said coil abutting against the end of said shell, a cup-shaped metal washer overlying said coil Within said shell and provided with an inner annular flange concentric with its outer wall and a plunger movable within said coil provided with a flanged end for engaging the flange of said washer simultaneously with the seating of said plunger against said core member, said method comprising securing the core member to the end of the shell within the coil, inserting the washer into said shell, introducing the plunger into said coil, pressing said plunger inwardly of said coil to first engage its flange with the flange of said washer and then move the latter inwardly of said shell until said plunger seats against said core member, and welding the outer wall of said washer to the inner surface of said shell in the position thus attained, whereby simultaneous seating of the plunger against said core member and the flange of said washer will thereafter be insured.

References Cited in the file of this patent UNITED STATES PATENTS 838,423 Kitsee Dec. 11, 1906 1,254,664 Downes Jan. 29, 1918 1,664,212 Hawkinson Mar. 27, 1928 2,101,130 Christman Dec. 7, 1937 2,111,232 Wetzel Mar. 15, 1938 2,113,167 Baumheckel Apr. 5, 1938 2,121,657 Fisher June 21, 1938 2,288,938 Claytor July 7, 1942 2,382,664 Ray Aug. 14, 1945 2,391,277 Stapleton Dec. 18, 1945 2,407,603 Derungs Sept. 10, 1946 2,449,438 Wisegarver Sept. 14, 1948 2,575,095 Charbonneau et al Nov. 13, 1951 FOREIGN PATENTS 867,141 France Oct. 1, 1941 

